The invention provides an energy-saving low-pressure extraction and cooling melamine production process, including a melamine reactor, a hot air cooler, a filter, a crystallizer, a trap, a carrier gas compressor, a cold air fan, a urine scrubber, a carrier gas heater, etc. . The upper part of the crystallizer has a double-layer cold air ring pipe, and the lower part of the crystallizer has a rotary scraper; the air intake of the carrier gas compressor and the air-conditioning fan are separated, the air intake of the air-conditioning compressor adopts hot process air, and the air intake of the air-conditioning fan adopts cold process air; From the outlet of the carrier gas preheater, a hot process gas is led out to distribute hot ammonia gas or superheated steam into the hot gas cooler and filter; the filters are set in series and parallel. The low-pressure extraction and cooling melamine production process device of the present invention has less construction investment, low consumption, high operating flexibility, high-grade product rate can reach 95%, and the continuous operation period of the device can reach more than 4 to 6 months.